tracing: Make sure variable string fields are NULL-terminated

The strncpy() currently being used for variable string fields can
result in a lack of termination if the string length is equal to the
field size.  Use the safer strscpy() instead, which will guarantee
termination.

Link: http://lkml.kernel.org/r/fb97c1e518fb358c12a4057d7445ba2c46956cd7.1522256721.git.tom.zanussi@linux.intel.com
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 6114939f065acf24b829cff156ddcec2b8a215e7..15ea11c29a51d5cd0e33764485a71dc96af941bf 100644 (file)
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -669,7 +669,7 @@ static notrace void trace_event_raw_event_synth(void *__data,
                        char *str_val = (char *)(long)var_ref_vals[var_ref_idx + i];
                        char *str_field = (char *)&entry->fields[n_u64];
 
-                       strncpy(str_field, str_val, STR_VAR_LEN_MAX);
+                       strscpy(str_field, str_val, STR_VAR_LEN_MAX);
                        n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
                } else {
                        entry->fields[n_u64] = var_ref_vals[var_ref_idx + i];
@@ -3091,7 +3091,7 @@ static inline void __update_field_vars(struct tracing_map_elt *elt,
                        char *str = elt_data->field_var_str[j++];
                        char *val_str = (char *)(uintptr_t)var_val;
 
-                       strncpy(str, val_str, STR_VAR_LEN_MAX);
+                       strscpy(str, val_str, STR_VAR_LEN_MAX);
                        var_val = (u64)(uintptr_t)str;
                }
                tracing_map_set_var(elt, var_idx, var_val);